Preparation of nickel carbonyl



Patented July 25, 1939 UNITED STATES PATENT OFFICE PREPARATION OF NICKELCARBONYL Application November 8, 1934, Serial No. 752,076 In GreatBritain November 11, 1933 5 Claims.

This invention relates to the separation of nickel carbonyl in theliquid phase from a mixture of gases and vapours containing it. Nickelcarbonyl is usually made by treating reduced nickel With carbon monoxideat atmospheric pressure, and it may be made by treating reduced nickel,or nickel matte or other impure source of nickel with carbon monoxide athigh pressure. The resultant gases contain nickel carbonyl together withsubstantial quantities of carbon monoxide and, if nickel matte or otherimpure source of nickel has been treated, impurities. If the nickelcarbonyl is to be separated instead of being immediately decomposed inthe way usual in the manufacture of nickel, it is liquefied underpressure or otherwise. Liquefaction may be desired either to lead toliquid nickel carbonyl as the final product or, in the case of nickelcarbonyl produced direct from mattes or the like, to purify the nickelcarbonyl before decomposing it to yield pure nickel. The principalobject of the present invention is so to conduct the liquefaction orcondensation that the maximum quantity of pure nickel carbonyl isobtained in liquid form.

The present invention is based on the remarkable discovery that thesaturated vapour pressure of nickel carbonyl is profoundly affected bythe partial pressure of carbon monoxide in contact with it. Thus it isfound that the vapour pressure decreases until the partial pressure ofcarbon monoxide reaches a certain critical value, but that when thepartial pressure increases above this value the vapour pressure of thenickel carbonyl again increases.

According to the present invention this discovery is applied to bringabout the liquefaction of the nickel carbonyl under conditions such thatits vapour pressure in the condensation space at the condensationtemperature is in the neighbourhood of a minimum so that the quantity ofliquid nickel carbonyl obtained is at or approaches its maximum for thetemperature in question. It is found that the variations in vapourpressure of the nickel carbonyl are conditioned solely by lowering ofthe pressure in accordance with the pressure at which the nickelcarbonyl is formed and the temperature of condensation, and theseparation of the liquid from the gaseous phase is effected at theselected higher or lower pressure. Thus the invention is essentiallydistinguished from processes in which nickel carbonyl formed underpressure is cooled at that pressure and subsequently reduced toatmospheric pressure in stages, since although it will then pass throughthe optimum pressure, i. e., that at which the maximum yield isobtained, separation is not effected at that optimum pressure. In somecases no adjustment of the pressure is necessary, since the nickelcarbonyl may be formed at the optimum condensation pressure and thencondensation and separation may take place at that pressure.

The relation between the partial pressure of carbon monoxide and thesaturated vapour pressure of nickel carbonyl is shown in theaccompanying drawing, which represents a graph of isotherms. The partialpressure of carbon monoxide While liquefaction is taking place isplotted isothermally against the nickel content of the gaseous or vapourphase in the liquefaction vessel, reckoned as grams of nickel per cubicmetre of gas at N.T.P. Since the gaseous phase may be assumed to besaturated with nickel carbonyl Vapour at the temperature underconsideration, the ordinates of the curves give a direct measure of thevapour pressure of nickel carbonyl at the condensation temperature. Itwill be appreciated that the parts of the curves shown in the drawingrepresent only a small part of the complete curves between 0 and 300atmospheres and that at very low pressures the vapour pressure of thenickel carbonyl is several times the minimum shown for the temperaturein question. The isotherms show a very Well defined minimum of nickelcarbonyl vapour pressure with respect to carbon monoxide partialpressure and according to the present invention the condensation of thenickel carbonyl is effected in the neighbourhood of this minimum at theparticular condensation temperature. Naturally to obtainthe best resultsthe pressure is maintained as near to the minimum as possible, but itwill be seen that, particularly at the lower temperatures, it ispossible to depart fairly substantially from the minimum and still toobtain yields that are relatively high and are far higher than thoseobtained at atmospheric pressure. It will be noted in particular thatbetween the temperatures of 0 to 40 C. the range of from 10 toatmospheres gives good results. Naturally it is often most convenient toeffect the condensation at about atmospheric temperature, but inpractice various factors have to be considered and when all these;

of using the drawing graphically, a convenient manner 'for determiningthe carbon monoxide partial pressure at which maximum condensation ofnickel carbonyl takes place'is to utilize an equation derived from thegraphs in'the drawing. Thus, the following empirical equation gives thelower limits of the range of carbon monoxide partial pressures at whichmaximum condensation of nickel carbonyl occurs: P:0.6T+22 in which:

T=the chosen condensation temperature P=the carbon monoxide partialpressure,

22=a constant.

This equation is derived from the graphs in the accompanying drawingwhich depicts a family of isotherms, as those skilled will readilyunderstand. It will be observed that for maximum yield of liquid nickelcarbonyl, the condensation takes place within the pressure range of 130atmospheres carbon 'monoxide partial pressure and 0.6T-1-22' atmospherescarbon monoxide partial pressure. Of course the total pressure at whichimaximum condensation occurs may be calculated, as those skilled in theart know, from the carbon monoxide content of the gases to be condensedand the aforesaid carbon monoxide partial pressure. The preferred limitswithin which the maximum yield of nickel carbonyl is obtained areindicated in the drawing by the area limited by lines AB and CD and theportions of isotherms segregated by the aforesaid lines 'AB and CD.

In order to show the advantage obtained by efiecting the condensation inthe neighbourhood of that carbon monoxide partial pressure which givesthe minimum nickel carbonyl vapour pressure, figures obtained with acertain gas mixture will now be given. Carbon monoxide gas containingnickel carbonyl equivalent to 500 gms. of nickel per cubic meter wasprogressively compressed at 20 C. and the liquidcarbonyl therebycondensed is shown in the following table:

Percent Ni 00) fi 00 pressure ats. hque e .It is clear from this tablethat the maximum condensation is obtained when the carbon monoxidepartial pressure is between 50 and 100 atmospheres, and this fact is ofcourse also shown by reference to the accompanying drawing. Further itwill be noticed that the yield at 25 atmospheres is distinctly greaterthan that at 200 atmospheres.

this.

In carrying the invention into effect either a batch process or acontinuous process may be used, the invention being in no way dependenton The carbonyl may be formed at lower pressures and then compressed sothat the carbon monoxide partial pressure brings the vapour pressure ofthe nickel carbonyl to the value desired or else the reaction may beconducted at higher pressures followed by expansion to the desiredpressure. Alternatively the concentration of carbon monoxide may bevaried in order to secure the partial pressure desired.

In order that the invention may be more readily understood two examplesof its application will now be given.

Example I obtain the maximum yield of nickel carbonyl;

these gases were compressed at 0 C. tothe optimum carbon monoxidepressure of 55 atmosj pheres and separation was then efiected. Theliquid nickel carbonyl obtained in this way was 95.4% of that in thegases.

Example II Carbon monoxide gases from a high pressure reaction vesselcontaining nickel carbonyl vapour in an amount equivalent to 450 gramsof nickel per cubic metre at a pressure of 250 atmospheres and at 80 C.were expanded to a pressure of '70 atmospheres "into a let-down vesselat atmospheric temperature. Separation was efiected at the pressure of'70 atmospheres and the amount of liquid nickel carbonyl obtained was94% of that in the gases.

We claim: V

1. The improved process for liquefying nickel carbonyl which comprisesreducing the pressure of gases containing carbon monoxide and about 450grams of nickel per cubic metre as condensible nickel carbonyl at areaction pressure of about 250 atmospheres total pressure and a reactiontemperature of about 80 C, to a condensation pressure equivalent to acarbon monoxide partial pressure of about '70 atmospheres atlacondensation temperature of about normal atmospheric temperature whilemaintaining said condensation temperature practically constant,liquefying said nickel carbonyl at said carbon densible nickel carbonylequivalent to about 420 grams of nickel per cubic metre at normaltemperature and pressure in accordance with the. carbon monoxide contentof said gases to an altered total pressure equivalent to a carbonmonoxide partial pressure of about55 atmospheres at a substantiallyconstant condensation temperature of about 0 C. to liquefy practicallyall of said condensible nickel carbonyl at said altered pressure, andseparating said liquid nickel carbonyl at said carbon monoxide partialpressure. V

3. The improved process for the production of nickel carbonyl whichcomprises reacting nickelcontaining material and carbon-monoxidecontaining gases at a reaction temperature and under a reaction pressureto obtain reaction gases containing carbon monoxide and condensiblenickel carbonyl, cooling said gases containing condensible nickelcarbonyl from said reaction temperature to a condensation temperature ofabout C. to about 80 C., altering the total pressure of said cooledgases from said reaction pressure to a condensation total pressuredependent upon the carbon monoxide content of said cooled gases andcorresponding to a carbon monoxide partial pressure between about 130atmospheres and a carbon monoxide partial pressure calculated from theequation, P=0.6T+22, while maintaining said condensation temperaturepractically constant, liquefying at least 90% of said condensible nickelcarbonyl at said altered pressure, and separating said liquefied nickelcarbonyl whilst maintaining said altered condensation pressuresubstantially constant whereby increased amounts of nickel carbonyl arerecovered.

4, A process for obtaining substantially complete condensation of nickelcarbonyl in the liquid phase from a mixture of gases including carbonmonoxide and nickel carbonyl which comprises establishing a body of saidgases at a condensation temperature between about 0 C. and about 80 C.and at a reaction pressure, altering said reaction pressure whilstmaintaining said condensation temperature practically constant to acondensation total pressure dependent upon the carbon monoxide contentof said body of gases and corresponding to a carbon monoxide partialpressure of about 22 to about 130 atmospheres, liquefying at least 90%of said condensible nickel carbonyl present at said altered pressure,and separating liquid nickel carbonyl from the overlying gas andresidual vapor mixture whilst maintaining and altered pressurepractically constant.

5. A process for obtaining substantially complete condensation of nickelcarbonyl in the liquid phase from a mixture of gases containing nickelcarbonyl and carbon monoxide under a total pressure in excess of 100atmospheres which comprises reducing the total pressure on said mixtureof gases to an altered total pressure dependent upon the carbonmonoxidecontent of said mixture and corresponding to a carbon monoxidepartial pressure between about 130 atmospheres and a carbon monoxidepartial pressure dependent upon a condensation temperature not greaterthan about 100 C. and calculated from the equation, P=0.6T+22,liquefying nickel carbonyl whilst maintaining said pressure practicallyconstant, and separating said liquefied nickel carbonyl whilstmaintaining said altered pressure substantially constant.

CHARLES F. R. HARRISON. ALBERT EDWARD WALLIS.

